Phenotype variation among siblings with 5-alpha reductase deficiency: A case series

Steroid 5α-reductase deficiency (5ARD) is a rare autosomal recessive disorder caused by mutation in the 5α-reductase type 2 gene (SRD5A2). 5ARD results in the impaired conversion of testosterone (T) to dihydrotestosterone (DHT) and is characterized by undervirilization in 46XY individuals. We report a case series of three siblings presenting with ambiguous genitalia and different phenotypes. They did not meet the widely accepted biochemical criteria for 5ARD. In view of strong clinical suspicion, genetic analysis was performed which revealed pathogenic mutation in SRD5A2. This report highlights the importance of definitive diagnosis with molecular methods as the treatment and prognosis differs greatly among the close differential diagnoses. Reliance on the biochemical criteria alone may lead to misdiagnosis.